Boyd A, Kendall K, Simon M I
Nature. 1983;301(5901):623-6. doi: 10.1038/301623a0.
Many biological processes depend on the function of proteins that detect changes in a cell's environment and transmit the information to the cytoplasm, for example, peptide hormone receptors. In Escherichia coli this class of proteins is exemplified by the sensory transducers (also called signalling proteins or methyl-accepting chemotaxis proteins) which have a central role in mediating chemotactic behaviour. The sensory transducers are the products of four genes: tsr, tar, tap and trg. Each transducer detects changes in the environmental concentration of one or a very few attractants: Tsr, serine; Tar, aspartate and maltose; Tap, unknown; and Trg, ribose and galactose. Tsr and Tar act directly as chemoreceptors for the amino acid attractants and signal changes in their degree of occupancy to the flagellar apparatus. Detection of these changes in occupancy is made possible as the transducers are methylated at multiple glutamate residues such that their level of methylation reflects the most recent chemoeffector concentration. Biochemical and genetic information concerning the serine transducer protein has been accumulating rapidly but little is known about the structure of the molecule. We present here the nucleotide sequence of the tsr gene of E. coli; the amino acid sequence derived from it suggests that the Tsr transducer protein has a relatively simple transmembrane structure that may place limits on the mechanisms available for the transmission of sensory information into the cell.
许多生物过程依赖于能够检测细胞环境变化并将信息传递到细胞质的蛋白质的功能，例如肽激素受体。在大肠杆菌中，这类蛋白质以感觉转导蛋白（也称为信号蛋白或甲基接受趋化蛋白）为代表，它们在介导趋化行为中起核心作用。感觉转导蛋白是四个基因的产物：tsr、tar、tap和trg。每个转导蛋白检测一种或极少数引诱剂在环境中的浓度变化：Tsr检测丝氨酸；Tar检测天冬氨酸和麦芽糖；Tap检测的引诱剂未知；Trg检测核糖和半乳糖。Tsr和Tar直接作为氨基酸引诱剂的化学感受器，并将其占据程度的变化信号传递给鞭毛装置。由于转导蛋白在多个谷氨酸残基处被甲基化，使得它们的甲基化水平反映了最近的化学效应物浓度，从而能够检测到这些占据程度的变化。关于丝氨酸转导蛋白的生化和遗传信息积累迅速，但对该分子的结构了解甚少。我们在此展示大肠杆菌tsr基因的核苷酸序列；由此推导的氨基酸序列表明，Tsr转导蛋白具有相对简单的跨膜结构，这可能限制了将感觉信息传递到细胞内的可用机制。
